Electroplate honing method

ABSTRACT

An electroplate honing technique that utilizes electrochemical honing to clean the metallic surface of a workpiece with current flow in one direction, then with the current flow reversed, utilizes an electroplate honing cycle to plate or deposit metal on the surface of the workpiece, then finally terminating the flow of current and utilizing a honing cycle to generate the surface finish desired by mechanical abrasion.

United States Patent Myron P. Ellis Royal Oak;

Richard J. Gavasso, Detroit, both of Mich. 838,1 13

July 1, 1969 Oct. 26, 1971 Micromatic Hone Corporation Detroit, Mich.

Inventors Appl. No. Filed Patented Assignee ELECTROPLATE HONING METHOD 3Claims, 5 Drawing Figs.

U.S. Cl 204/26, 204/143 G, 204/217, 204/224 Int. Cl C23b 5/56, B23p1/00,B23p1/02 Field of Search 204/26,

References Cited UNITED STATES PATENTS 3,022,232 2/1962 Bailey et al.204/26 3,267,018 8/1966 Greening 204/217 3,313,715 4/1967 Schwartz, Jr.204/26 FOREIGN PATENTS 1,216,063 5/1966 Germany 583,872 1/1947 GreatBritain Primary Examiner-John H. Mack Assistant E.raminerT. TufarielloAnorney.lames l-l. Bower ABSTRACT: An electroplate honing technique thatutilizes electrochemical honing to clean the metallic surface of aworkpiece with current flow in one direction, then with the current flowreversed, utilizes an electroplate honing cycle to plate or depositmetal on the surface of the workpiece, then finally terminating the flowof current and utilizing a honing cycle to generate the surface finishdesired by mechanical abrasion.

PATENTEUum 25 mm SHEET 3 OF 3 CURRENT HIGH i STONE PRESSURE TOOL SOURCEOF D.C. POWER CLEANING E 6 R WEW 3 N 005 Z LTE SR P 2 Z m o T T T m L RR R o O E U M C C P R l U 0 N 5 M PLATING.

HIGH STONE PRESSURE OFF SOURCE OF D.C. POWER GENERATION OF SURFACEFINISH INVENTORS MY/POA/ A [14/5 /?/C//ARO J. aAa Asso ATTORNEYELECTROPLATE HONING METHOD BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to the honing art and more particularlyto an electroplate honing method whereby the surface of the metal isfirst cleaned by a combined electrochemical machining and honingprocess, then plated so that the plated surface is mechanically honed orcut to the desired surface characteristics.

2. Description of the Prior Art It is known and recognized to utilizeplating and burnishing or polishing at the same time. That is, thesurface of the material is polished or burnished at the same time thatthe plating solution is pumped into the environmental area. Otherprocesses involve a simultaneous burnishing and plating operation whilethe workpiece is immersed in a plating solutron.

SUMMARY OF THE INVENTION According to the present invention, theelectroplate honing method combines the surface cleaning characteristicsof electrochemical honing, the high metal deposition rate of highcurrent density electroplating and the accurate abrading of honing. Iteliminates the need for acid etching ofthe surface to be plated and/orthe masking of adjacent surfaces. The metal is deposited only onsurfaces in close proximity to the electrode. The electrode in thisinstance is also the honing tool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front perspective view ofan electroplate honing apparatus made in accordance with the principlesof the present invention;

FIG. 2 is a fragmentary perspective view of a workpiece being operatedby the electroplate honing tool to illustrate the principles of thepresent invention;

FIG. 3 is a schematic representation of the typical plating cycle inwhich the surface of the workpiece is being cleaned;

FIG. 4 is a schematic representation in which the surface of theworkpiece is being plated;

FIG. 5 is a schematic representation showing the surface of theworkpiece being abraded without the benefit of any electroplating orelectrochemical means.

GENERAL DESCRIPTION FIG. I shows a perspective view of an illustrativeembodiment which comprises a hollow base generally indicated by thenumeral on which is mounted a column generally indicated by the numeral11. As shown, the numeral 12 generally indicates a spindle and/or ramassembly on which is operatively mounted a tool spindle generallyindicated by the numeral 13. A tool member generally indicated by thenumeral 14 is connected to the spindle 13. The tool member 14 extendsdownwardly into operative engagement with the workpiece 16 held in aworkpiece fixture 17 that is disposed in a transparent fixture enclosure15. The workpiece 16 is illustrated as comprising a gear. The honingapparatus includes means for reciprocating and rotating the tool member14 relative to the workpiece 16 as described in detail hereinafter. Thetool member 14 carried means for maintaining it in a spacedapartposition relative to the surface of the workpiece 16 which is beingmachined in a manner described in US Pat. No. 3,390,068, issued to M. P.Ellis et al. on June 25, 1968, and assigned to the present assignee ofthe application. As described hereinafter, the plating solution issupplied to the gap or space between the tool 14 and the workpiecesurface during the machining operation and direct current issimultaneously passed between the workpiece l6 and the tool member 14 asdescribed hereinafter.

As shown in FIG. I, the spindle head assembly 12 is slidably mounted forvertical reciprocating movement on a pair of vertical, spaced apartguide members 17 and 18. The spindle head assembly 12 includes thecentral housing 19 on each side of which is integrally formed thevertically disposed guide sleeves 20 and 21.

The spindle head assembly 12 is adapted to be reciprocated upwardly anddownwardly by a pair of hydraulic cylinders not shown but described inthe hereinabove mentioned US. Pat. to Ellis et al., No. 3,390,068. Itwill be understood that the hydraulic cylinders may be operated andcontrolled by any suitable hydraulic controlled circuit means. Anillustrative control circuit which may be employed to operate thehydraulic cylinders is shown in FIG. 51 of the hereinabove mentionedpatent to Ellis et al.

The machine used is basically a honing machine such as described in theabove mentioned patent. A rectifier supplies the direct current to theoperation. During plating the honing tool acts as the anode, having apositive potential, and the workpiece is the cathode. The platingsolution is pumped into the gap between the tool and the surface beingplated.

A typical plating cycle is as follows:

1. A short deplating period, approximately 10 seconds, is used to cleanthe surface by an electrochemical honing process such as described inthe above-mentioned patent to Ellis et al. The honing tool at this timeis negative and the workpiece is positive as shown in FIG. 3. The toolis expanded so that the stones 22 are abrading the surface 23 of theworkpiece 16. The plating solution is flooding the tool and theworkpiece at the gap between the surface 23 of the workpiece and thetool 14,

2. At the end of this time period the direction of current flow is nowreversed so that the workpiece has a negative potential as shown in FIG.4. The pressure of the honing stones 22 is reduced. Consequently, metalis plated onto the surface uniformly at a rate depending on the solutionbeing used, the current density, and in some cases the temperature ofthe solution. The stones are in a low stone pressure state therebyabrading the surface throughout the plating cycle to eliminate treeing,refine the grain structure of the plated metal and generate accurategeometry.

3. When the bore is plated to the desired size, the flow of current isterminated and the pressure on the stones 22 is increased, as shown inFIG. 5, to generate the surface finish desired. That is, in the laststages there is no current flow between the tool and the workpiece,consequently, the only generation of surface finish is done bymechanical abrading.

Any amount of metal may be plated onto the surface that is kept clean bythe honing stones. Termination of the plating may be achieved by apredetermined timing cycle or an automatic in-process gaging.

Plating Rate Time to Deposit Materials Plated 0.00 l Thickness As shownin FIG. 2, the pressure of the honing stones may be accomplished bymovement of a cone means 30 connected to a rod 31 slidable in tool 14.The rod 31 is connected to a piston 33 slidable in chamber 35. Movementof piston 33 is upward or downward directions is caused by providingfluid pressure through lines 37 and 39, depending on the direction ofmovement. The tool 14 is itself totally reciprocated and rotated in amanner well known in the art and in the above mentioned patent to Elliset al.

For purposes intended, the description and drawings hereinabove isrelated to finishing the interior bore surface of a workpiece, however,the method described herein can be applied to other structures, such asexterior surfaces of a cylindrical or spherical object, and flat plainsurfaces.

What is claimed is:

1 in a method for finishing the surface of a workpiece with a toolhaving an electrically conductive tool body portion and at least oneabrasive member supported by and adjustable outwardly from said toolbody portion comprising the steps of:

1. providing relative movement between the honing tool and the worksurface;

2. maintaining said electrically conductive tool body portion in aspaced relationship to the work surface;

3. flowing a plating solution between the work surface and theelectrically conductive tool body portion;

4. passing a direct electric current from the work surface to theelectrically conductive tool body portion through said plating solutionto remove metal electrochemically from the work surface; keeping theabrasive member abrading the work surface to clean said work surface;

5. reversing the current flow so that the workpiece is negativepotential and the tool is positive potential so that metal is platedonto the surface of the workpiece, keeping the abrasive member abradingthe work surface with an adjustment in pressure during plating to keepthe surface clean, refine the grain structure of the plated. material,and correct errors in geometric shape;

6. terminating the supply of direct current flow; and,

. advancing the abrasive member with increasing pressure onto the worksurface to remove the metal mechanically from said work surface andgenerate a controlled cut surface finish.

2. A method of plating and electrochemically honing a metallic worksurface with a honing tool having an electrically conductive tool bodyportion and at least one abrasive member supported by and adjustableoutwardly from said tool body portion, comprising the steps of:

1. providing relative movement between the honing tool and the worksurface;

2. maintaining said electrically conductive tool body portion in aspaced relationship to the work surface;

3. advancing the abrasive member into abrasive engagement with the worksurface to remove metal mechanically from the work surface;

4. flowing a plating electrolyte between the work surface and theelectrically conductive tool body portion;

5. passing a direct electric current from the work surface to theelectrically conductive tool body portion through said platingelectrolyte to remove metal from the work surface and clean said surfacemechanically and electrochemically;

6. reversing the flow of said direct electric current from said worksurface to said electrically conductive tool to plate said work surface;

7. applying low abrasive pressure against said work surface as said worksurface is being plated;

8. terminating the supply of direct electric current;

9. applying a high abrasive pressure against said work surface; and

i0. retracting the abrasive member after a predetermined time interval.

3. A method of honing a metallic work surface with a honing tool havingan electrically conductive tool body portion and at least one abrasivemember supported by and adjustable outwardly from said tool bodyportion, comprising the steps of:

l. rotating and reciprocating the honing tool over the work surface;

2. maintaining said electrically conductive tool body portion in aspaced relationship to the work surface;

3. advancing the abrasive member into honing engagement with the worksurface to remove metal mechanically from the work surface;

4. flowing a plating solution between the work surface and theelectrically conductive tool body portion; 5. passing a direct electriccurrent from the work surface to the electrically conductive tool bodyportion through the plating solution to remove metal from the worksurfaces;

6. reversing the supply of direct electric current;

7. terminating the supply of direct electric current when the diameterof the bore is at the desired size; and

8. retracting the abrasive member after a timed interval.

2. A method of plating and electrochemically honing a metallic worksurface with a honing tool having an electrically conductive tool bodyportion and at least one abrasive member supported by and adjustableoutwardly from said tool body portion, comprising the steps of: 2.maintaining said electrically conductive tool body portion in a spacedrelationship to the work surface;
 2. maintaining said electricallyconductive tool body portion in a spaced relationship to the worksurface;
 2. maintaining said electrically conductive tool body portionin a spaced relationship to the work surface;
 3. advancing the abrasivemember into honing engagement with the work surface to remove metalmechanically from the work surface;
 3. flowing a plating solutionbetween the work surface and the electrically conductive tool bodyportion;
 3. advancing the abrasive member into abrasive engagement withthe work surface to remove metal mechanically from the work surface; 3.A method of honing a metallic work surface with a honing tool having anelectrically conductive tool body portion and at least one abrasivemember supported by and adjustable outwardly from said tool bodyportion, comprising the steps of:
 4. flowing a plating electrolytebetween the work surface and the electrically conductive tool bodyportion;
 4. passing a direct electric current from the work surface tothe electrically conductive tool body portion through said platingsolution to remove metal electrochemically from the work surface;keeping the abrasive member abrading the work surface to clean said worksurface;
 4. flowing a plating solution between the work surface and theelectrically conductive tool body portion;
 5. passing a direct electriccurrent from the work surface to the electrically conductive tool bodyportion through the plating solution to remove metal from the worksurfaces;
 5. reversing the current flow so that the workpiece isnegative potential and the tool is positive potential so that metal isplated onto the surface of the workpiece, keeping the abrasive memberabrading the work surface with an adjustment in pressure during platingto keep the surface clean, refine the grain structure of the platedmaterial, and correct errors in geometric shape;
 5. passing a directelectric current from the work surface to the electrically conductivetool body portion through said plating electrolyte to remove metal fromthe work surface and clean said surface mechanically andelectrochemically;
 6. reversing the flow of said direct electric currentfrom said work surface to said electrically conductive tool to platesaid work surface;
 6. terminating the supply of direct current flow;and,
 6. reversing the supply of direct electric current;
 7. terminatingthe supply of direct electric current when the diameter of the bore isat the desired size; and
 7. advancing the abrasive member withincreasing pressure onto the work surface to remove the metalmechanically from said work surface and generate a controlled cutsurface finish.
 7. applying low abrasive pressure against said worksurface as said work surface is being plated;
 8. terminating the supplyof direct electric current;
 8. retracting the abrasive member after atimed interval.
 9. applying a high abrasive pressure against said worksurface; and
 10. retracting the abrasive member after a predeterminedtime interval.